A Micromachined Acoustic Multiplexer for Ultrasound and Photoacoustic Imaging Applications

In this letter, we report the design, fabrication, and testing of a novel micromachined silicon-based acoustic multiplexer. The acoustic multiplexer is capable of selectively transmitting ultrasound signals traveling in multiple acoustic channels one at a time. This makes it possible to send and/or receive multiple channels of ultrasound signals in a serial manner with only one single-element ultrasound transducer, followed by single channel of data acquisition electronics. An eight-channel acoustic multiplexer was constructed and the switching performance of the multiplexer was tested with ultrasound transmission experiment. An excellent signal ON/OFF ratio of 6.5 was achieved between two adjacent acoustic channels. The functionality of acoustic multiplexer in ultrasound imaging system was demonstrated by conducting photoacoustic imaging on an optically absorptive target inside an optical phantom. The micromachined acoustic multiplexer could be a useful component in designing new ultrasound transceiver systems for imaging applications.